I think that in the game, you should have a device and be able to talk (shout!!) at the players, telling them of any individual order changes etc, etc...
If though, you happen to swear too much :D ,or you get sent from the dugout and react badly, you should be fined, banished to the stands or both. Then, when you make changes you have to ring by mobile phone and you talk to the assistant manager.
There should also be a manager cam, allowing you to switch to your view from the sidelines or from the stands for those naughty gaffers out there :D :p , and then you can toggle your view by pressing the arrow keys (if you know what I mean)
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(If I was manager of Manchester United, they would win everything, including the FIFA World Club Championship)